Automatic-balance brake



A. McCANN.

AUTOMATIC BALANCE BRAKE.

APPLICATION FILED SEPT. 19, I918.

Patented Feb. 10, 1920.

2 SHEETS-SHEET 1- TIE DH m w N l WITNESSES n n W A. McCANN.

AUTOMATIC BALANCE BRAKE.

APPLICATION HLED SEPT. 19. 1918.

1,330,641. Patented Feb. 10,1920.

2 SHEETS-SHEET 2.

fi/ucluio/o M Q A MC6a/7/7 ANDREW MCCANN, OF NOR'II-IBEN D, WASHINGTON.

AUTOMATIC-BALANCE BRAKE.

Application filed September 19, 1918.

To all whom it may concern:

Be it known that I, ANDREW MGCANN, a citizen of the United States, and aresidentoi Northbend, in the county ofKing and State of ld ashington,have invented a new and Improved Automatic-Balance Brake, of which thefollowing is a full, clear, and eXact description.

This invention relates to vehicle brakes and particularly to anautomatic balance brake mechanism which 'acts to avoid uneven brakeapplication so as to obviate skidding and other diiiiculties in slipperytraffic as Well as to promote even wear and thus increase the life aswell as the effectiveness of the brakes.

A. further object of the invention is the provision of an arrangement bywhich the balanced action of the brakes will be automatic and wherebythe same. requires minimum attention and with practically no adjustmentbeyond that occasioned by ordinary wear.

A still further object of the invention is to provide a construction inwhich there will be no dragging of the brakes and each of the wheelswill be caused to act evenly as the wheel resistance of the road isautomatically balanced when the brake is applied.

In the accompanying drawings:

Figure 1 is a top plan view of a brake mechanism embodying theinvention, the same being shown applied.

Fig. 2 is a detail sectional viewv of an actuating sliding pedal and itsframe, same disclosing certain features of the invention.

Fig. 8 is a front elevation of the brake mechanism associated with oneof the wheels of the vehicle shown in Fig. 1.

Fig. 4 is a side view of the mechanism shown in Fig. 3, part of theupper casing being broken away for better illustrating certain featuresof the invention.

Referring to the accompanying drawings by numerals 10 indicates a brakedrum rigidly secured in any desired manner to the respective wheels 34and 85, there being one housing for each wheel and identical mechanismassociated therewith so that the description of one housing and one setof mechanism will equally apply to both. This mechanism is shown indetail in Figs. 3 and 4 to which special reference is made. Associatedwith the drum 10 is a flange 11 rigidly secured to the axle casing 11,said Specification of Letters Patent.

Patented Feb. 10, 1920.

Serial No. 254,727.

flange of course being stationary and fitted loosely in the drum 10shown at the bottom of Fig. 3 so that the drum 10 may rotate with thewheel freely. Any suitable form of emergency brake may be used andarranged interiorly of the drum 10, said emergency brake mechanismforming no part of the present invention, in Fig. 4 a lever 8 andoperating rod 9 being shown. Arranged at the upper part of the drum 10is a casing 12 which is rigidly secured to the flange 11 by any suitablemeans, as for instance rivets as shown in Fig. 4, said casing having aninwardly bent portion 14 through which suitable hook bolts 14 extend,said hook bolts interlocking with one end of the respective retractilecoil springs 13 and 13. The opposite ends of these springs are connectedto the flexible cables 21, which cables in turn pass through suitableopenings in the casing 12 and over guiding pulleys 22 so that theopposite'ends may be rigidly secured in any suitable manner to thebrackets 20 of the upper section 15 of the brake band. A pair of coils46 are arranged in casing 12 and act against said casing as hereinafterfully described, said springs being connected at One end of the casingand at the opposite end to a connecting bar or shoe 47 so that whenspring 13 expands to a certain extent the same will engage the bar 47 sothat the springs 46 will begin to act.

The brake drum 10 connected with the wheel is provided with a brake bandformed in two parts, namely an upper semi-cylindrical section 15 havingbrackets 20 as shown in Fig. 4 and a lower semi-cylindrical section 16having brackets 20 constructed similar to the brackets of section 15.The sections are so proportioned that the brackets 20 of the respectivesections will be spaced ashort distance apart, said sections 15 and 16being of course on opposite sides of the axle 17 and the casing 11'.Each of these sections carries its respective section 19 of the brakelining, so that when the sections are forced toward the drum 10 agripping action will be provided, said action being in proportion to themovement of said sections.

The respective brackets 20 are threaded, the opposing brackets beingprovided wlth right and left hand threads respectively for receiving therespective screw shafts 23 which are provided with rightand left handthreads, so that upon a rotation of these shafts sections 15 and 16 willbe moved toward each other or away from each other so as to apply ordisengage the brake band. Adjacent the lower ends of the respectivescrew shafts 23 spur gears 31 are provided, said gears being rigidlysecured to the respective shafts 23 and positioned to engage the rackface of the rack bars 32, said rack bars extending across the face offlange 11 and engaging simultaneously both of the gears 31 so that bothgears will be operated at the same time and to the same extent, wherebythe respective screw shafts will be moved so that the respective pairsof brackets 20 will be simultaneously spread or brought toward eachother. It will be evident that when the rack bars 32 are moved in onedirection the screws 23 will be moved for causing the brake band to beapplied and when moved in the opposite direction will cause the brakeband to be disengaged.

A pair of supporting bars 24 and 25 are pivotally connected at 26 to theflange 11, said fulcrum 26 being arranged at the centers of therespective bars. These supporting bars are provided with horizontallyextending e iensions 27 and 28 at each end, said extensions havingapertures through which the screw shafts 23 extend, whereby the lowerset of projections 28 act as suports for the shafts 23 and associateparts.

he 28 each end of the respect. bars 24 and 25 are connected by uprights29, said connections being pivotal and of any desired structure, as forinstance an ord nary bo t extending through an aperture in the uprightsand threaded intothe respecti e extensions 28. Each of the upri hts isprovided near its lower end with a recess or groove 30 as s o n in 3 foraccommodating the rear face of the rack bar 32 whereby the same isproperly supported it slides back and forth. addition to this supportthe rack bar 32 is provided with an overlapping flange 32 which rests onthe respective spur gears 31.

Each of the rack bars 32 is provided with aspring which is secured atone end to the respective rack bars as shown more particularly in Fig. 1and at the opposite end to the lower section 16 of the brake bands.These springs act to move the rack bar rearwardly so as to release thebrake band when the pedal 45 and associate parts are released. Inaddition these springs act to cause the balancing of the braking efiectas hereinafter fully described. The respective rack bars 32 arepivotallv connected at 37 to a transverse brake beam 38 which providedwith a yoke 39 at a central point,

said yoke being pivotally connected at 40 to a forwardly extendingconnecting rod 41. The connecting rod 41 is pivotallv connected at 42 toa slide block .43 carried by the parallel guide rods 44 supported in anydesired manner on the vehicle. The pedal 45 is preferably pivotallyconnected to the slide block 43 and is positioned so as to be readilyoperable from the operating station of the vehicle, whereby whenever theoperator desires to apply the brake he may press upon the pedal 45 andmove the block 43 forwardly. This will pull on the rod 41 and also onthe brake beam 38 so as to cause a forward motion of the respective rackbars 32. This forward motion of the rack bars 32 will rotate therespective spur gears 31 and move the sections 15 and 16 ad acent eachwheel toward the drum 10 connected to each wheel for producing a brakingaction, the amount of movement of the sections 15 and 16 being inproportion to the amount of movement of the pedal 45. When it is desiredto release the brake mechanism the operator removes his foot from thepedal 45 and springs 36 return the respective parts to their formerposition and will cause a positive release or unclutching of the brakeband.

By reason of the pivotal connections at 37 and pivotal connections at 40there will. be an automatic balancing of the strain and consequently anautomatic balancing of the braking action. In addition to this automaticdistribution of the strain and consequent braking action the arrangementof the spring 36. rack bars and associate parts will produce anadditional automatic balancing of the braking action. For instance ifone of the brake bands does not grip entirely properly for any reason,as for instance by reason of having too much oil thereon the oppositeband will be rotated somewhat by reason of its engagement with the drum10 as there is more tension on that particular wheel. This rotation ofthe brake band will bring the particular spring 36 connected with theabove mentioned brake band under tension and said extra tension willcause the rack bar 32 connected with spring 36 to move rearwardly andconsequently cause the spur gears 31 and the screw shafts 23 to rotatesufficiently to re lease the brake bands associated therewith so thatadditional strain will be brought on the brake band which is slipping.In this way the respective brake bands will have applied theretoasuflicient strain to cause the respective wheels to be equalized orbalanced in their resistance. In this way the respective brake shoes arebalanced, but the emergency brake connected with lever 8 and rod 9 isnot balanced, but is operated the same as is usual on cars only from thebottom instead of half way up. The balancing of the emergency brake isnot necessary, as the service'brake will hold all that the roadconditions will allow when the streets are s rp y- It will be noted thatwhen the streets are slippery, or for some reason the automaticbalancing of the brake is necessary and the sections 15 and 16 begin torotate cable 21 will begin to move and bring the spring 13 undertension, if the movement is sufiicient said spring will engage bar 47and check further movement by reason of the action of spring 46, saidchecking however being yielding in order to prevent a sudden stop of themovement. When the vehicle is moving in an opposite direction the sameaction takes place, spring 13 will act, but as the momentum of thevehicle is less than in the forward movement the springs 46 andassociate parts are not necessary. The control spring 36 attached to thelower quarter of the band, namely section 16, and the other end attachedto the rack 32 are under considerable tension when the brakes are setand the strain is equally divided until one wheel offers more resistancethan the other. When this occurs the wheel with the least resistancenaturally gives way, the tension of the sprin 's on top of the drum andthe springs on t e brake band and rack of the other wheel is increasedand the result is the slacking of one and the automatically tighteningof the other until a balance is secured.

I claim as my invention:

1. A vehicle brake, comprising a two section band, means connecting saidsections to move them toward and away from each other, a pair of springsanchored at one end and flexibly connected at their opposite ends to onebrake band section, and normally inactive tension means in the path ofmovement of one of the springs for the purpose described.

2. A vehicle brake comprising a brake band in upper and lower sectionshaving opposing end pieces, means connecting said end pieces to movesaid sections toward and away from one another, and a pair of springsanchored at one end and flexibly connected at their opposite ends to theopposite end pieces of the upper brake band section, and normallyinactive tension means in the path of movement of one of the springs forthe urpose described.

3. A brake comprising a brake housing, a pair of supporting armsfulcrumed adjacent their center above and below the center of saidhousing, upper and lower brake band sections having opposing endextensions provided with threaded openings, screw shafts havingoppositely threaded portions extending through the said threadedopenings and having their ends journaled in the ends of said supportingarms and means to simultaneously rotate said screw shafts, as described.

4. A brake comprising a brake housing, a pair of supporting armsfulcrumed adjacent their centers above and below the center of saidhousing, upper and lower brake band sections havlng opposing endextensions provided with threaded openings, screw shafts havingoppositely-threaded portions and having their ends journaled in the endsof the said supportin arms, gears carried by the said screw sha ts, andsliding rack bars engaging said gears for rotating the same and saidscrew shafts.

5. A brake comprising a brake housing, a pair of supporting armsfulcrumed adjacent their centers above and below the center of saidhousing, upper and lower brake band sections havlng opposing endextensions provided with threaded openings, screw shafts havingoppositely-threaded portions and having their ends journaled in the endsof the said supporting arms, gears carried by the said screw shafts,sliding rack bars engaging said gears for rotating the same and saidscrew shafts, and upright guide members connecting the ends of saidsupporting arms, and in which the said rack bars have guided movement,as described.

ANDREW MoCANN.

